```jsx {3,7,14}
export function Popover() {
  // initial focused element ref
  const inputRef = useRef(null)

  const service = useMachine(popover.machine, {
    id: "1",
    initialFocusEl: () => inputRef.current,
  })

  // ...

  return (
    //...
    <input ref={inputRef} />
    // ...
  )
}
```
